In recent years, the electronic product is widely used in society, and most people use the electronic product in daily life. The electronic product has a circuit therein. Whether the circuit is simple or complicated, the circuit usually includes a passive device such as a resistance device, a capacitance device, an inductance device or an overcurrent and overvoltage protective device, etc.
In regard to the overcurrent and overvoltage protective device, it is used to prevent the sophisticated electronic product from being damaged and protect the circuit and elements in the circuit when a transient overcurrent or overvoltage is occurred. The overcurrent and overvoltage protective device includes a safety fuse made of alloy material. When a transient current exceeds a predetermined value, the heat energy caused by the transient overcurrent will melt the safety fuse, and thus the circuit is broken. Such that, the overcurrent can't flow into the circuit, thereby preventing the electronic product from being damaged.
In general, a breaking capacity test is performed for the manufactured overcurrent and overvoltage protective device to determine whether the insulation impedance of the overcurrent and overvoltage protective device is qualified or not. The breaking capacity test is varied according to the type or the demand of the electronic product. In the breaking capacity test, a high power is applied, and the safety fuse of the overcurrent and overvoltage protective device will be transitorily melted, thereby resulting in an arcing effect. The arcing effect will generate very high temperature, thereby melting alloy, flux and so on in fuse, and then inducing more conductive material, increasing conductive path between electrodes, decreasing the insulation between the electrodes, and even generating the short circuit between the electrodes when the cross-electrode in fuse is melted. If the fuse is not completely disconnected by the arcing effect (i.e. impedance between the electrodes is less than 1 MΩ), the fuse can't provide protect function, and the electronic elements of the electronic product may be damaged since the electronic elements may continuously and dangerously work. Therefore, it is an important topic to resolve the problem.